This invention relates to a router constituting an IP (Internet Protocol) network. More specifically, the invention relates to a method and device to sort traffic by service type at a node between a server site and an IP network, thereby controlling the flow rate of each stream of traffic and ensuring a response to users for each service type.
A QoS (Quality of Service) function of a router is employed to ensure quality of respective services provided via a network. With the QoS function, packets of individual services are assigned their respective bandwidths on a connection line so that a high priority service can preferentially be delivered to users.
The QoS function is a function for per-flow bandwidth control and per-flow priority control. The term flow refers to a group of packets that have the same combination of a TCP (Transmission Control Protocol) or UDP (User Datagram Protocol) port number and a sender or receiver IP address. The QoS function can be used by both the input side network interface which receives a service request and the output side network interface which is connected to a server.
In the case where a single server providing a plurality of services receives and processes many packets of one of the services that is low in priority from users' point of view, the load of this service could take up most of the server's processing resource and lower the quality of other services that hold high priority for users. It is therefore desirable when a plurality of services shares a server's processing resource to give different priority levels to different services and preferentially deliver a high priority service to users.
For instance, consumption of an entire line bandwidth by a file transfer using FTP (File Transfer Protocol), which is employed for large-capacity file transfer, can be avoided by limiting a bandwidth that is occupied by FTP to 30% of the line bandwidth at maximum while allocating the rest to HTTP (Hyper Text Transfer Protocol), which is used as an interface of a service application, and to SMTP (Simple Mail Transfer Protocol), which is used to fetch e-mail.
To set a priority level to each service, a server-connected network interface of a router puts, through the QoS function, a limit to how much of a bandwidth is occupied by packets of each service and thereby indirectly limits how much of a server resource is occupied by each service.
A router has a control unit composed of a CPU and peripheral devices of the CPU. The control unit processes such route control protocols as OSPF (Open Shortest Path First) and BGP (Border Gateway Protocol), and provides a setting/management user interface using telnet or HTTP. As network services are diversified, a router is enhanced in function by incorporating a server that is composed of a CPU or a network processor, and software of the CPU or the network processor. The incorporated server is connected to a network interface via a switch interface that is located inside the router.
The QoS function of the router can be applied to the server incorporated in the router to ensure the quality of each service provided by the server. In this case, it will raise the cost of the router to provide every server with a mechanism for executing the QoS function.
In the case where an existing router configuration is employed to avoid an increase in cost, communication quality is ensured for each service by performing uniform, or utilization-history-basis, bandwidth control on a plurality of network interfaces that receives request packets from users.